Which one of the following is not an example for response to stimulus?

Question

$\begin{array}{1 1} \text{a. Watering in mouth when we see delicious food items} \\ \text{ b. Closing of leaves of Mimosa when touched.} \\ \text{ c. Shutting of eyes when an object is suddenly thrown i our direction} \\ \text{ d. A chick hatching out of egg.} \end{array}$